diff options
Diffstat (limited to 'migration/ram.c')
| -rw-r--r-- | migration/ram.c | 46 |
1 files changed, 35 insertions, 11 deletions
diff --git a/migration/ram.c b/migration/ram.c index 6e3dc845c5..5379164749 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -2452,9 +2452,14 @@ static void postcopy_preempt_reset_channel(RAMState *rs) * a host page in which case the remainder of the hostpage is sent. * Only dirty target pages are sent. Note that the host page size may * be a huge page for this block. + * * The saving stops at the boundary of the used_length of the block * if the RAMBlock isn't a multiple of the host page size. * + * The caller must be with ram_state.bitmap_mutex held to call this + * function. Note that this function can temporarily release the lock, but + * when the function is returned it'll make sure the lock is still held. + * * Returns the number of pages written or negative on error * * @rs: current RAM state @@ -2462,6 +2467,7 @@ static void postcopy_preempt_reset_channel(RAMState *rs) */ static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss) { + bool page_dirty, preempt_active = postcopy_preempt_active(); int tmppages, pages = 0; size_t pagesize_bits = qemu_ram_pagesize(pss->block) >> TARGET_PAGE_BITS; @@ -2485,22 +2491,40 @@ static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss) break; } - /* Check the pages is dirty and if it is send it */ - if (migration_bitmap_clear_dirty(rs, pss->block, pss->page)) { - tmppages = ram_save_target_page(rs, pss); - if (tmppages < 0) { - return tmppages; - } + page_dirty = migration_bitmap_clear_dirty(rs, pss->block, pss->page); - pages += tmppages; + /* Check the pages is dirty and if it is send it */ + if (page_dirty) { /* - * Allow rate limiting to happen in the middle of huge pages if - * something is sent in the current iteration. + * Properly yield the lock only in postcopy preempt mode + * because both migration thread and rp-return thread can + * operate on the bitmaps. */ - if (pagesize_bits > 1 && tmppages > 0) { - migration_rate_limit(); + if (preempt_active) { + qemu_mutex_unlock(&rs->bitmap_mutex); + } + tmppages = ram_save_target_page(rs, pss); + if (tmppages >= 0) { + pages += tmppages; + /* + * Allow rate limiting to happen in the middle of huge pages if + * something is sent in the current iteration. + */ + if (pagesize_bits > 1 && tmppages > 0) { + migration_rate_limit(); + } + } + if (preempt_active) { + qemu_mutex_lock(&rs->bitmap_mutex); } + } else { + tmppages = 0; + } + + if (tmppages < 0) { + return tmppages; } + pss->page = migration_bitmap_find_dirty(rs, pss->block, pss->page); } while ((pss->page < hostpage_boundary) && offset_in_ramblock(pss->block, |